1. Field of the Invention
The present invention relates to an apparatus for calculating how much a central axis of an obstacle detecting apparatus for a vehicle deflects from the centerline of the vehicle along a longitudinal direction, in which the obstacle detecting apparatus is mounted on the vehicle and serves to radiate a transmission wave over a given angular range from a given central axis to the width direction of the vehicle for detecting a distance to and an angle of an obstacle in response to a reflected wave from the obstacle. The invention also relates to a deflection of central axis correcting apparatus for correcting the deflection of central axis of the obstacle detecting apparatus. Further, the invention relates to an inter-vehicle distance control system for controlling a distance between a system vehicle equipped with the system and a vehicle ahead of the system vehicle on the basis of the central axis of the obstacle detecting apparatus the deflection of which has been corrected.
2. Description of the Related Art
An obstacle detecting apparatus is designed to be mounted on a vehicle and to serve to radiate a transmission wave, such as an optical wave or an electromagnetic wave, over a forward detection zone defined by a given angle to the width direction of the vehicle for detecting a distance to and an angle of an obstacle such as a preceding vehicle on the basis of a reflected wave from the obstacle. This type of obstacle detecting apparatus is used in an inter-vehicle distance control system for detecting a preceding vehicle ahead of a system vehicle equipped with the system and holding a distance between the vehicles at a constant value, or in a warning control system for issuing an alarm when the system vehicle moves into proximity to an obstacle.
Such an obstacle detecting apparatus must be mounted on a vehicle such that the central axis of the apparatus is exactly in line with the centerline of the vehicle along the longitudinal direction. If the control axis deviates from the center line, an error in detecting an angle of the obstacle appears. In this case, the obstacle detecting apparatus may recognize a vehicle traveling along an adjacent lane as the preceding vehicle, or it may recognize the preceding vehicle as an object other than the preceding vehicle.
However, a highly accurate adjustment is required to put the central axis of the obstacle detecting apparatus exactly in line with the centerline of the vehicle along the longitudinal direction, and therefore a problem arises because this installation takes a significant amount of time.